ABO Typing Discrepancies (Online CE Course)

(based on 3,205 customer ratings)

Author: Candice Freeman, MLS(ASCP)BBCM, CQA(ASQ)
Reviewer: Barbara Cebulski, MS, MLS(ASCP)CM

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Discrepancies in ABO typing lead to delays in determination of products that are safe to transfuse to the patient. When the ABO type has not clearly been determined, transfusion of universal donor red cells and plasma are necessary, thus depleting the supply of these products. It is important to know the possible causes of ABO discrepancies in order to develop algorithms and standard procedures to resolve them quickly. This course will provide a general scheme for resolving ABO discrepancies and work through examples cases.

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Continuing Education Credits

P.A.C.E.® Contact Hours (acceptable for AMT, ASCP, and state recertification): 2 hour(s)
Approved through 9/30/2021
Florida Board of Clinical Laboratory Personnel Credit Hours - General (Blood Banking / Immunohematology): 2 hour(s)
Approved through 9/1/2022


  • Demonstrate knowledge and understanding of ABO testing and result interpretation.
  • Identify the types of ABO discrepancies and explain the impact that discrepancies can have upon patient care and patient safety.
  • Accurately and efficiently detect an ABO discrepancy and apply serological techniques to resolve the error to ensure the correct ABO type is reported.
  • Discuss how different test methodologies, including tube, column agglutination, and solid phase, produce varying results with regard to discrepant ABO types.
  • Analyze preanalytical, analytical, and postanalytical steps to uncover a potential ABO discrepancy.

Customer Ratings

(based on 3,205 customer ratings)

Course Outline

Click on the links below to preview selected pages from this course.
  • Introduction
      • Course Overview
  • Basics of Immunology and ABO Testing
    • Immunology Principles
    • ABO Testing
      • ABO Groups and Frequencies
      • ABO Testing and Interpretation
      • Review the following test results and match the expected reaction pattern to the reported ABO type.
  • ABO Typing Discrepancies
      • ABO Typing Discrepancies
      • Classifying ABO Discrepancies
      • ABO Discrepancies Related to Subgroups of A or B
      • Weakened or Missing Reactions in the Reverse Typing
      • Acquired B Phenomenon
      • Plasma Protein-Related Discrepancies
      • Miscellaneous Causes of ABO Discrepancies
      • A patient's pretransfusion ABO grouping results are as follows:Forward (Cell) GroupingReverse (Serum) GroupingAnti-AAnti-BAnti-A,BA1 CellsB Cells4+04+...
  • Resolution Strategies
  • Comparison of Testing Methodologies
  • Case Studies: Resolving Discrepancies on the Bench
      • Case Study Review and Performance
      • Case Study 1An 83-year-old female is undergoing pre-op testing which includes a type and screen with a 2-unit Red Cell crossmatch. One 7mL EDTA tube w...
      • Case Study 2A 38 year old female patient has a history of chronic anemia which has resulted in 4 previous allogenic packed red blood cell transfusions...
      • Case Study 3 A 36 year old man has a history of gastrointestinal conditions including Crohn's Disease. He has been admitted to the hospital for a gene...
      • Case Study 4 A 44 year old woman has a history of Rheumatoid arthritis and chronic anemia, historically treated with diet and iron supplements. She ha...
      • Case Study 5 A 48-year-old woman has been hospitalized with an infection of Mycoplasma pneumoniae. At the patient's request, her physician has ordered...
  • References
      • References

Additional Information

Level of instruction: Intermediate

Intended Audience: Medical laboratory scientists, medical technologists, and technicians. This course is also appropriate for medical laboratory science students and pathology residents.
Author information: Candice Freeman, MLS(ASCP)BBCM, CQA(ASQ) is an instructor in the Medical Laboratory Technology Program at Sandhills Community College, Pinehurst, NC. She has many years of clinical laboratory experience, mainly as a blood bank and microbiology technologist. She has also held the position of Laboratory Manager/Laboratory Administrator. Candice holds a BS degree in Clinical Laboratory Science from Winston-Salem State University and is completing a Master’s program in Education in New Media and Global Education, Instructional Design Specialist.
Reviewer information: Barbara Cebulski, MS, MLS(ASCP)CM has recently retired as a Program Director for MediaLab, Inc., located in Lawrenceville, GA. She has over 30 years experience in the medical laboratory profession as a technologist, section supervisor, and laboratory manager. She also was employed for nine years by the College of American Pathologists in the Laboratory Accreditation Program. Barbara holds a Masters in Instructional Technology from Georgia State University. 

How to Subscribe
MLS & MLT Comprehensive CE Package
Includes 139 CE courses, most popular
$95Add to cart
Pick Your Courses
Up to 8 CE hours
$50Add to cart
Individual course$20Add to cart
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